The development of new ceramic materials is sometimes hindered by the ability to reproducibly synthesize high quality starting powders. The ability to control the solid morphology of materials formed from powders is largely dependent upon controlling particle size and size distribution. Control is also dependent upon minimizing particle-particle interaction. Small particles with a narrow range of particle size distribution are generally desired. Alternatively, a good distribution of particle sizes may include relatively large particles which form the bulk of the material as well as smaller particles used for filling the interstitial spaces between the larger particles during manufacture.
A number of methods have been developed to form monodispersed powders (i.e., particles with a narrow range of particle size distribution and low tendency toward agglomeration) by chemical methods such as the controlled homogeneous precipitation of metal oxides from metal alkoxide by hydrolysis in organic liquid systems. These methods prove to be quite good at producing high purity metal oxide powders. In many cases, however, the conditions which are favorable for metal alkoxide hydrolysis, and the subsequent metal oxide precipitation, are not amenable to minimizing particle-particle interactions. Consequently, the powders form agglomerates and become polydispersed. Other attempts to produce monodispersed metal oxide powders using the technique of metal alkoxide hydrolysis have involved the use of mechanical stirrers to disperse the aqueous phase in the organic liquid system. These techniques are energy intensive and generally do not produce metal oxide powders with the desired size distribution.